GRE_issue必背新概念22篇.doc

精选可编纂Lesson2Sparethatspider不要损害蜘蛛Why,youmaywonder,shouldspidersbeourfriends?Becausetheydestroysomanyinsects,andinsectsincludesomeofthegreatestenemiesofthehumanrace.Insectswouldmakeitimpossibleforustoliveintheworld;theywoulddevourallourcropsandkillourflocksandherds,ifitwerenotfortheprotectionwegetfrominsect-eatinganimals.Weowealottothebirdsandbeastswhoeatinsectsbutallofthemputtogetherkillonlyafractionofthenumberdestroyedbyspiders.Moreover,unlikesomeoftheotherinsecteaters,spidersneverdotheharmtousorourbelongings.Spidersarenotinsects,asmanypeoplethink,norevennearlyrelatedtothem.Onecantellthedifferencealmostataglance,foraspideralwayshaseightlegsandinsectnevermorethansix.Howmanyspidersareengagedinthisworknoourbehalf?OneauthorityonspidersmadeacensusofthespidersingrassfieldinthesouthofEngland,andheestimatedthatthereweremorethan2,250,000inoneacre;thatissomethinglike6,000,000spidersofdifferentkindsonafootballpitch.Spidersarebusyforatleasthalftheyearinkillinginsects.Itisimpossibletomakemorethanthewildestguessathowmanytheykill,buttheyarehungrycreatures,notcontentwithonlythreemealsaday.IthasbeenestimatedthattheweightofalltheinsectsdestroyedbyspidersinBritaininoneyearwouldbegreaterthanthetotalweightofallthehumanbeingsinthecountry.你能够会感到惊奇，蜘蛛怎样会是咱们的冤家呢？因为它们能毁灭那么多的虫豸，此中包含一些人类的年夜敌，要不是人类受一些食虫植物的爱护，虫豸就会使咱们无奈在地球上生涯下去，虫豸会吞食咱们的全体庄稼，杀逝世咱们的成群的牛羊。咱们要特不感激那些吃虫豸的鸟跟兽，然而把它们所杀逝世的虫豸全体加在一同也只相称于蜘蛛所毁灭的一小局部。其余，蜘蛛差别于其余食虫植物，它们丝绝不迫害咱们跟咱们的财物。很多人以为蜘蛛是虫豸，但它们不是虫豸，乃至与虫豸毫有关联。人们简直一眼就能看出二者的差别，因为蜘蛛基本上8条腿，而虫豸的腿从不超越6条。有几多蜘蛛在为咱们效能呢？一位研讨蜘蛛的威望对英国南部一块草坪上的蜘蛛作了一次考察。他估量每英亩草坪里有225万多只蜘蛛。这的确是说，在一个足球场上约有600万只差别品种的蜘蛛。蜘蛛至多有半年在忙于吃虫豸。它们一年中毁灭了几多虫豸，咱们简直无奈猜想，它们是吃不饱的植物，不称心一日三餐。据估量，在英国蜘蛛一年里所毁灭虫豸的分量超越谁人国度生齿的总分量。Lesson5Youth青年Peoplearealwaystalkingabout'theproblemofyouth'.Ifthereisone--whichItakeleavetodoubt--thenitisolderpeoplewhocreateit,nottheyoungthemselves.Letusgetdowntofundamentalsandagreethattheyoungareafterallhumanbeings--peoplejustliketheirelders.Thereisonlyonedifferencebetweenanoldmanandayoungone:theyoungmanhasagloriousfuture